Petefls



L PEYERS, PHOTO-LITHOGRAPHER. WASHINGTON, n C,

NAPEIERS, PHOTO-LITHOGRAPHER, wA'SmNGToN. n c.

A'UruTED sTATEs PATENT OFFICE.

ROBERT GRIFFITHS, OF LONDON, ENGLAND.

PROPELLER.

Specification of Letters Patent No. 17,016, dated April 7, 1857.

To all 'whom t may concern Be it known that I, ROBERT GRIFFITHS, of London, England, have invented certain Improvements in Propellers for Vessels, reference being had to the accompanying drawings, making part of this speciiication, in which-g j l Figure 1 is a side elevation of myimj proved propeller, Fig. 2 a longitudinal, and Fig. 3 a transverse section thereof. Fig. 4L is an elevation of a modification of my improved propeller with the blades inclined forward toward the vessel. Fig. 5 `is an elcvation of another modification. Figs. 6 and 7, end and a longitudinal elevation of another modification, with two blades inclined forward and two inclined backward. Figs. 8 and 9 represent a propeller lwith some of my improvements but with the blades of the ordinary form. And Fig. 10 represents a propeller with my improved form of I blades secured to the ordinary boss or hub. 1

As propellers were made prior to myinl vention, the blades were either attached to a hub of a diameter simply sufficient to secure the required strength, or to the cir-v cumference of a hoop connected with thel shaft or hub by arms twisted in the form of a helix. Under all the Variet-ies of form in which these two classes of propellers have i been constructed and applied, they present serious difficulties and objections. The surfaces of the blades, by their helical form; or any form approximating to a helix, approach the line of the plane of the axis of 1 the shaft, as they converge toward the axis, and when the boss or hub is made of ai diameter merely suflicient for strength thel `blades at their junction therewith so nearly j approach parallelism with the axis of the shaft, that the power exerted by them on the water at and near the surface of the boss is so nearly at rightangles with the line of the vessels motion as to be wasteful of power, and when the blades are attached j to the periphery of a hoop, the arms connecting the hoop with theV shaft or hub present the same diiiiculty, and in both classes the centrifugal action on the water` near the center is known to be prejudicial to the propelling action. I am enabled in s a great measure to avoid these diiculties and to attain other advantages by my inl vention, the iirst part of which consists in making a propeller with the blades attached to an enlarged and hollow boss or hub, sayl of about one third the entire diameter of the propeller. This places the point of attachment of the blades with the boss or hub so far from the axis of the shaft as to avoid all the evil consequences due to attachment of the blades as are due to a small `boss or hub, while at the same time it admits of the combination which constitutes the second part of my invention and which con.- sists in connecting the blades with the enlarged hollow boss or hub by means of a stem on each blade, tted to turn in the said enlarged boss for the purpose of adjusting the pitch of theblades to the condition of t-he vessel and the power of the engines. And the third part of my said invention also consists in so connecting the stems of the blades within the enlarged boss or hub with a governor to render the pitch of the blades self adjusting. And the last part of my invention consists in connection with a large hollow boss or hub in making the blades of propellers narrower toward their outer ends. By this means the serious inconveniences which have been experienced in the use of blades as heretofore made with their outer ends wider are avoided. As the angle which the face of the blades makes to the line of the keel increases toward their outer ends, it follows that when the vessel is moving exclusively under sail and the propeller is not in action, .that the wider the blades are toward their outer ends, the greater will be the resistance which they will present to the sailing of the vessel.

`blow by making the blades narrower toward their outer ends, they will present much less resistance to the sailing of the vessel, while for the purposes of propelling the reduction of the extent of surface can be toward the outer ends and is compensated by their in creased width toward their inner ends, and by increased velocity. Again, when the blades are made, as heretofore, widest at their extreme ends, but little clearance is left between them and the stern and rudder po-rts, the clearance being less and less when the rotative velocit-y is greatest- This produces a violent, injurious and disagreeable vibration at the stern of the vessel, which vibration is greatly reduced by this part of my invention, whereby the clearance is increased toward the ends of the blades when the velocity is greatest. `1 1 l In the accompanying drawings (a.) represents the boss which is a hollow metal sphere suitably and firmly secured on the shaft (o). This boss is formed with suitable sockets to receive theshanks (c) of the blades (CZ) so that they can turn therein. The stems have arms (e) fitted to an inner boss or hub (f) which slides on the shaft within the boss (a) and the outer end of these arms act on a box (g) which slides longitudinally in the shaft (Z9) and acts against a collar (2') held by the lever (71;) which is connected to the governor spring (la) inside the vessel j by a rod (Z) provided with an adjusting Y collar This sliding motion is controlled by the spring (7c) placed within the engine room or other suitable position which is regulated to the proper resistance by the adjusting screw (m) in the rod (Z). Now whenever the propeller blades meet with less resistance by reason of favorable winds or currents, the speed of the engine increases and the increased speed of the propeller throws a proportional increase of pressure on the leading side of the blades greater than ,theV adjusted resistance of the governor spring (Ic) which is compressed by the rod (Z) forced forward by the sliding box (g) against the collar Thus the pitch increases until the propeller throws a greater load on the engine and instantly reduces the number of revolutions, simultaneously with which the differential pressure between the leading and after portion of the blades is diminished, and thev governor spring (lo) forcing back the sliding box (g) adjusts the true pitch of the propeller blades to the former and proper speed of the engine, which by this means has always its full eect-ive power made available under all circumstances of currents and winds.

The blades (eZ) are gradually narrower toward their outer ends and their faces of p the usual twist. I prefer to have but two such'blades, one opposite the other so that ywhen the Vessel is to sail alone the shaft can 4be turned until the two blades are in the 1vertical plane of the stern post, and when 'inl disposition the blades being made narrow-toward their outer ends where the plane of their surface is at the greatest angle with the line of motion of the vessel, they will present much less resistance or drag to the sailing of the vessel than when made,

. as heretofore, and it will be seen also that this form of blades will leave much more clearance toward their outer ends where the velocity is greatest thus greatly reducing the.

Vmay be inclined forward and two back as` represented at Figs. 6 and 7. Or each blade may be made wider and divided toward the outer end to give the required taper as represented at Fig. 5.

The mode of applying my improvements in the enlargement of the boss with the usual form of blades is represented by Figs. 8 and 9 and the mode of applying the improved form of blade with the usual hub is represented at Fig. 10.`

Although I prefer the selfacting arrangement by which the pitch of the propeller blades is adjusted, nevertheless, this one part of my invention may be dispensed with andthe other parts retained to advantage, in which oase the method of connecting the blades with the hollow enlarged boss will admit of applying any suitable means for adjusting and setting the pitch of the propeller blades to the best average condition of the vessel and engine.

Although I prefer the form of a sphere the enlarged hollow boss as described and represented, I do not wish to confine myself to such special form as the same ends may be obtained by a spheroidal, conical or egg shape. Nor do I wish to be understood as limiting myself to the placing of the whole of the enlarged boss in the shaft, as the forward and rear parts may be fixtures to the dead wood and rudder post. Nor do I wish to be understood as limiting myself to the number, position or special form of the blades, so long as they are constructed and operate on the principle and accomplish the purpose I have in View under merely formal variations.

What I claim as my invention and desire to secure by Letters Patent, is-

1. Making propellers with an enlarged boss on the shaft to which the blades are secured, extending say to `about one third of the entire diameter substantially as specified and this I claim in contra-distinction to the solidhub of a diameter merely suflicient for strength as heretofore employed, whereby I avoid the centrifugal or broken action of the water near the center which is known to be prejudicial to the propellingA action of the blades, and by which also I avoid the resistance due to the action of the blades near the center where they otherwise would be in a plane nearly coincident with the plane of the axis of the shaft.

2. And I also claim in combination with an enlarged boss, substantially as herein described, the method of connecting the blades therewith by means of a shank or stem, on

the blades, fitted to and capable of being turned in the said boss to adjust the pitch Y propeller blades With the lenlarged hollow boss or hub, and the selfadjusting apparatus, substantially as herein specied.

4. And I also claim in combination with the enlarged hollow boss or hub, the blades narrowed toward their outer ends, and the round shank attachment to the hub, as herein specied.

RoBT. GRIFFITHS. [La] Signed sealed and delivered in the presence of- JOHN R. DARKER, WM. EWING. 

